TREATMENT OF DANDRUFF AND SEBORRHEIC ERUPTIONS 449 riohal objections concern, the lack of uniform positive results of inocula- tion, interpretation of the induced skin lesions, usually a transitory ery- thematous scaly lesion, "like seborrheic dermatitis," lack of proof that the organism cultured from the lesion, the site of inoculation, was not on the skin before inoculation, possibility of error of identification of the inocu- lated organism and difficulty of proof. It is to be noted that Benham (14) expressed the opinion that the strain employed by Moore belonged to Group III Cryptococcus. Dowling (20) subsequently realized (in 1939) that the strain he employed was not Pityrosporum ovale, but M. pinoyi. This repudiation by Dowling is apparently not widely known since the original report of MacLeod and Dowling is still quoted. Others have reported negative results. Ota and Huang (9) were unable to obtain more than transient erythema with their inoculations. Ben- ham (14) tried to produce lesions, but without result. Emmons (15) rubbed the organism into the scalp and skin of seborrheic subjects, but was unable to demonstrate that it had any pathogenic properties. Rocha and co-workers (19) could not demonstrate pathogenic properties of Pityrosporum ovale on inoculation experiments. As later discussed, negative results are reported by Martin-Scott (17) and by Leone (18). The most recent studies of Pityrosporum ovale in relation to dandruff are those of Martin-Scott (17), Leone (18) and of Whitlock (4). Martin-Scott's publication is a comprehensive review in addition to cultural studies of the organism, its morphology, its resistance to antisep- tics, antibiotics and fVngicides, its taxonomy and nomenclature. He observed that the addition of sodium tauroglycocholate or ox bile to Sabouraud's medium permits excellent growth. The organism was cultured from normal adults as frequently as from seborrheic subjects much less frequently from lesions of acute seborrheic dermatitis than from lesions of the chronic form of the disease. The organism was demonstrated by culture from a variety of scaly and greasy dermatoses. Attempts to recover it from the scalps of normal babies under one year were not successful, but cultures were obtained from the scalps of babies under one year who had infantile eczema. It was not possible to produce any reaction from application of the patient's own strain of organ- ism on the skin. Intracutaneous tests were not done since the organism could not be demonstrated histologically in the dermis in seborrheic derma- titis and the course of the disease suggests a superficial spread. Martin- Scott expressed the opinion that a positive reaction to an intracutaneous injection would not help in proving the pathogenicity of the organism. He concludes that the organism has been cultured from healthy animals, and experiments on laboratory animals suggest that it is nonpathogenic to them. Human experiments indicate that it is a nonpathogenic saprophyte, which fails to fulfill Koch's postulates as the cause of seborrheic dermatitis.

450 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Leone's study (18) is another comprehensive review of the relation of Pityrosporum ovale to dandruff with cultural and biochemical studies of the organism. Pityrosporum ovale was isolated from normal skin and from a variety of scaly lesions other than seborrheic dermatitis. A quantitative determination of Pityrosporum ovale was made in rela- tion to the number of scales and their lipid content. The increase in number of organisms correlated ]ipid content of scales. The organism presence in ear wax was regarded as confirmatory evidence of this relation. Inoculation of culture into human skin and into guinea pigs failed to demonstrate pathogenicity. It is concluded that Pityrosporum ovale is a saprophyte of the normal skin and its increase in pathologic processes is connected with the increase of lipold content of steatotic scales. Whitlock (4) studied degree of Pityrosporum ovale infection by micro- scopic examination of scales from the scalps of 200 subjects. The number of organisms were graded, as well as the degree of dandruff. His study showed a sharp rise in the incidence of dandruff and degree of Pityrosporum ovale infection at puberty. He attributed this not to a causal relation of the two conditions, but more likely to increase of sebaceous activity at that age since the organism is lipophilic. It was observed that of 30 cases with seborrhea of the scalp all except one showed a heavy Pityrosporum ovale infection, and that 38 out of 49 cases with some degree of hair loss showed the same finding. Forty-eight males and 33 females showed slight or no dandruff in the presence of heavy Pity- rosporum ovale infection. He found comparable degrees of Pityrosporum ovale infection on the skin of the nose (a region rich in sebaceous glands) without scaling or other abnormality. As later discussed, dandruff disappears or diminishes during pregnancy. Whitlock correlated the degree of Pityrosporum ovale infection with degree of dandruff in 32 pregnant women. Dandruff was absent or slight in 19 and was graded 1 plus and 2 plus (his maximum gradation was 3 and 4 plus) in 13. From this study he concluded that increase in circulating estrogen during pregnancy plays no part in determining the degree of infection of the scalp with Pityrosporum ovale. Whitlock states the opinion that his investigations support the thesis that Pityrosporum ovale has nothing to do with the cause of dandruff, seborrhea, or seborrheic dermatitis. He believes that dandruff represents the normal desquamation of the scalp, similar to the "invisible" scaling on other parts of the skin caused by normal replacement of cornified cells. The difference lies in the retention of the scales by the hair of the scalp, a suggestion which seems to derive support from the shorter hair and more frequent scalp washing in the male, who shows a lower incidence of heavy dandruff in comparison with the long-haired female whose scalp is washed less often lest her "waves" should cease to remain permanent.